Method of manufacturing copper wiring in a semiconductor device

ABSTRACT

A method of manufacturing copper wiring in a semiconductor device by forming a diffusion prevention film on a damascene pattern, forming a first copper film by a PVD method, forming a second copper film by a spin-on coating method, and forming a third copper film by a PVD or electrochemical deposition method. The method provides a good coverage characteristic and can prevent generation of voids etc., thus improving reliability of the device.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates generally to a method of manufacturingcopper wiring in a semiconductor device. More particularly, theinvention relates to a method of manufacturing copper wiring in asemiconductor device, which has a good coverage characteristic and canprevent generation of voids, etc., and thus is capable of improvingreliability of a device, by which a diffusion prevention film is formedon a damascene pattern, a first copper film is formed by a PVD method, asecond copper film is formed by a spin-on coating method, and a thirdcopper film is formed by PVD or an electrochemical deposition method.

[0003] 2. Description of the Prior Art

[0004] A prior art method of manufacturing a copper wiring in aconventional semiconductor device is explained below with reference toFIG. 1.

[0005] An insulating film 12 is formed on a semiconductor substrate 11in which a predetermined structure is formed. Then, a predeterminedregion of the insulating film 12 is patterned by a dual damasceneprocess to form a trench through which the predetermined region of thesemiconductor substrate is exposed. Next, a diffusion prevention film 13is formed on the entire structure, including the trench. Thereafter, aseed layer 14 is formed by means of a PVD method. Then, a copper film 15is formed by an electochemical deposition method so that the trench canbe completely filled. Next, after the copper film 15 is cured by anannealing process, it is polished by a CMP process to form copperwiring.

[0006] If the copper wiring is formed by the above process, the coveragecharacteristics of the diffusion prevention film and the seed layerformed by CVD method are degraded as the device is highly integrated.Therefore, the diffusion prevention does not function properly or copperatoms 16 enter the insulating film through the diffusion preventionfilm. Due to this, when the copper layer is formed by an electrochemicaldeposition method, a void 17 is created which adversely affectsreliability of the wiring.

[0007] Also, the copper layer is formed by an electrochemical depositionmethod after the diffusion prevention film and the seed layer areformed, and breakage of vacuum is caused to form a copper oxide film 18on the seed layer. Therefore, even after the copper layer is depositedby an electrochemical deposition method, the copper oxide film 18 existswithin the wiring, thus adversely affecting reliability of the device.In addition, as the copper layer formed by electrochemical deposition isformed using additives, many impurities exist in the deposited copperlayer to adversely affect the copper metal layer.

[0008] It is expected that as the device is highly integrated, theconventional method becomes difficult to use. Therefore, there is a needfor a copper wiring method that has better coverage and results in fewerimpurities.

SUMMARY OF THE INVENTION

[0009] A method of manufacturing a copper wiring in a semiconductordevice includes the steps of forming an insulating film on asemiconductor substrate in which a given structure such as an underlyingconductive film is formed, and then sputtering the insulating film by adual damascene process to form a trench through which the underlyingconductive layer of the semiconductor substrate is exposed; removing ametal oxide film remaining on the exposed underlying conductive layer toform a diffusion prevention film; after forming a first copper film onthe entire structure, forming a second copper film and performing anannealing process until a desired thickness is formed, thus forming acopper oxide film on the second copper film; removing the copper oxidefilm to form a third copper film on the entire structure; and polishingthe third, second and first copper films, and the diffusion preventionfilm by CMP process to form a copper wiring.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1 is a cross-sectional view for explaining a method ofmanufacturing a copper wiring in a conventional semiconductor device;and

[0011]FIGS. 2A to 2D are cross-sectional views for explaining a methodof manufacturing a copper wiring in a semiconductor device according tothe present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0012] It is an objective of the disclosure to provide a method ofmanufacturing a copper wiring in a semiconductor device that has bettercoverage and fewer impurities.

[0013] A method of manufacturing a copper wiring uses a spin-on coatingmethod and a PVD method. A diffusion prevention film formed using theCVD method can improve a coverage characteristic, a copper layerdeposited using spin-on coating method can solve the problems of the PVDmethod, and a flat copper layer formed by PVD method can improve thecharacteristic of a deposited copper layer.

[0014] The present invention will be described in detail by way of apreferred embodiment with reference to accompanying drawings.

[0015] Referring to FIG. 2A, an insulating film 22 is formed on asemiconductor substrate 21 in which a predetermined structure such as anunderlying conductive layer, etc. is formed. Then, a predeterminedregion of the insulating film 22 is patterned by a dual damascenemethod, thus forming a trench through which the underlying conductivelayer of the semiconductor substrate 21 is exposed. After a metal oxidefilm formed on the underlying conductive layer is removed, a diffusionprevention film 23 is formed by a CVD method without vacuum breakage.With this process, a uniform coverage is obtained to prevent copper fromdiffusing. In order to remove a metal oxide film in the underlyingconductive layer, inert reduction gases such as a mixture gas of H₂ andAr or a mixture gas of H₂ and He, etc. are used. Also, the diffusionprevention film may be formed using materials such as Ta, TaN, TiAlN,WN, TiSiN, WBN, TaSiN, etc. and is formed in a thickness of less than100 Å.

[0016] Referring to FIG. 2B, after a first copper film 24 is formed onthe entire structure by a PVD method without a vacuum breakage, a secondcopper film 25 is formed by spin-on coating method and is cured by anannealing process. The second copper film 24 is formed in thickness ofless than 100 Å. The second copper film 25 is formed in a thickness ofabout 500 Å to about 2000 Å by spin-on laminating copper-containingorganic solvent. The annealing process is performed for removing theorganic solvent after the second copper film 25 is formed, which issequentially performed in the coating equipment at a temperature ofabout 100° C. to about 350° C. If this annealing process is performed,contraction of its volume is caused due to vaporization of the solvent,thus forming a copper film having a high density. The spin-coatingprocess and the annealing process are repeatedly performed until adesired thickness is obtained. If these processes are performed, acopper oxide film 26 is formed on the second copper film 25 formed bythe coating. Meanwhile, after the second copper film 25 is formed by aspin-on coating method, it is cured by an annealing process in annealingequipment at a temperature of about 350° C. to about 450° C. under argonor a mixture gas of argon and hydrogen atmosphere for about 10 minutesto about 60 minutes.

[0017] Referring to FIG. 2C, after the second copper film 25 is formed,a plasma process is performed using a reduction gas such as hydrogen atthe etching chamber of sputtering equipment. Then, the copper oxide film26 formed on the second copper film 25 is completely removed. Next, athird copper film 27 flattened by a PVD method is formed on the entirestructure. The third copper film 27 is formed with the temperature of awafer maintained in the range of about 300° C. to about 450° C. in orderto maintain diffusion of copper and characteristic of the insulatingfilm, and the thickness thereof is in the range of about 5000 Å to about15000 Å for facilitating a subsequent CMP process. The copper filmdeposited at high temperature as above, has a higher degree of purity ina copper metal than that by the electrochemical deposition and has acoarse crystal particle. Thus, it does not need an additional annealingprocess.

[0018] Referring to FIG. 2D, unnecessary copper and diffusion preventionfilm are removed by CMP. After the CMP process is performed, a processof protecting copper may be performed while the surface of copper isreduced using a gas such as NH₃.

[0019] In the above, meanwhile, though the flattened third copper filmis formed by PVD method, the third copper film may be formed by anelectrochemical deposition.

[0020] As mentioned above, the method can form copper wiring having avery low CuO content since it forms all the copper films using theequipment used conventionally, and does not require an additionalannealing process for a copper film of a fine structure since it forms acopper film at high temperature without forming the copper film by anelectrochemical method. Also, it can form a copper film havingreliability of a wiring improved since it performs several annealingprocesses.

[0021] The method has been described with reference to a particularembodiment in connection with a particular application. Those havingordinary skill in the art and access to the teachings of the disclosurewill recognize additional modifications and applications within thescope thereof.

[0022] It is therefore intended by the appended claims to cover any andall such applications, modifications, and embodiments within the scopeof the invention.

1. A method of manufacturing copper wiring in a semiconductor device,comprising the steps of: providing a semiconductor substrate in which apredetermined structure is formed, said substrate having an underlyingconductive layer, forming an insulating film on said substrate,patterning said insulating film by a dual damascene process to form atrench through which the underlying conductive layer of saidsemiconductor substrate is exposed, said conductive layer having a metaloxide film remaining thereon; removing the metal oxide film remaining onthe exposed underlying conductive layer to form a diffusion preventionfilm; forming a first copper film on the entire structure; thereafterforming a second copper film and performing an annealing process until adesired thickness is formed, thus forming a copper oxide film on saidsecond copper film; removing said copper oxide film to form a thirdcopper film on the entire structure; and polishing said third, second,and first copper films, and said diffusion prevention film by a CMPprocess to form copper wiring.
 2. The method of claim 1, comprising thestep of removing said metal oxide film remaining on said underlyingconductive layer using a gaseous mixture of H₂ and Ar or a gaseousmixture of H₂ and He.
 3. The method of claim 1, wherein said diffusionprevention film is formed a film selected from the group consisting ofTa films, TaN films, TiAlN films, WN films, TiSiN films, WBN films, andTaSiN films by a CVD method.
 4. The method of claim 1, comprising thestep of forming said diffusion prevention film in a thickness below 100Å.
 5. The method of claim 1, comprising the step of forming said firstcopper film in a thickness below 100 Å by a PVD method.
 6. The method ofclaim 1, comprising the step of forming said second copper film in athickness of about 500 Å to about 2000 Å by spin-on laminating acopper-containing organic solvent.
 7. The method of claim 1, comprisingthe step of sequentially performing said annealing process at atemperature of about 100° C. to about 350° C. in the coating equipment.8. The method of claim 1, further including an annealing process iscarried out in annealing equipment at a temperature of about 350° C. toabout 450° C. under an atmosphere of argon or a mixture gas of argon andhydrogen for about 10 minutes to about 60 minutes, after said secondcopper film is formed.
 9. The method of claim 1, comprising the step ofremoving said copper oxide film by performing a plasma process usingreduction gas in an etching chamber of sputtering equipment.
 10. Themethod of claim 1, further including, after said CMP process isperformed, the step of performing a process of protecting the surface ofcopper while it is reduced using a NH₃ gas.
 11. The method of claim 1,comprising the step of forming said third copper layer in a thickness ofabout 5000 Å to about 15000 Å with the substrate maintained at atemperature of about 300° C. to about 450° C.
 12. The method of claim11, further including, after said CMP process is performed, the step ofperforming a process of protecting the surface of copper while it isreduced using a NH₃ gas.
 13. The method of claim 1 comprising the stepof forming said third copper film by an electrochemical depositionmethod.